title: 18F-FDG PET/CT for detection of malignant peripheral nerve sheath tumours in neurofibromatosis type 1: tumour-to-liver ratio is superior to an SUVmax cut-off.
abstract: OBJECTIVE
  To evaluate the usefulness of normalising intra-tumour tracer accumulation on (18)F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) to reference tissue uptake for characterisation of peripheral nerve sheath tumours (PNSTs) in neurofibromatosis type 1 (NF1) compared with the established maximum standardised uptake value (SUVmax) cut-off of >3.5.
  
  
  METHODS
  Forty-nine patients underwent FDG PET/CT. Intra-tumour tracer uptake (SUVmax) was normalised to three different reference tissues (tumour-to-liver, tumour-to-muscle and tumour-to-fat ratios). Receiver operating characteristic (ROC) analyses were used out to assess the diagnostic performance. Histopathology and follow-up served as the reference standard.
  
  
  RESULTS
  Intra-tumour tracer uptake correlated significantly with liver uptake (rs= 0.58, P = 0.016). On ROC analysis, the optimum threshold for tumour-to-liver ratio was >2.6 (AUC = 0.9735). Both the SUVmax cut-off value of >3.5 and a tumour-to-liver ratio >2.6 provided a sensitivity of 100 %, but specificity was significantly higher for the latter (90.3% vs 79.8%; P = 0.013).
  
  
  CONCLUSIONS
  In patients with NF1, quantitative (18)F-FDG PET imaging may identify malignant change in neurofibromas with high accuracy. Specificity could be significantly increased by using the tumour-to-liver ratio. The authors recommend further evaluation of a tumour-to-liver ratio cut-off value of >2.6 for diagnostic intervention planning.
  
  
  CONCLUSIONS
  • (18)F-FDG PET/CT is used for detecting malignancy in PNSTs in NF1 patients • An SUV max cut-off value may give false-positive results for benign plexiform neurofibromas • Specificity can be significantly increased using a tumour-to-liver ratio.
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany, j.salamon@uke.de.
authors.forename: Johannes
authors.initials: J
authors.lastname: Salamon
authors.forename: Simon
authors.initials: S
authors.lastname: Veldhoen
authors.forename: Ivayla
authors.initials: I
authors.lastname: Apostolova
authors.forename: Peter
authors.initials: P
authors.lastname: Bannas
authors.forename: Jin
authors.initials: J
authors.lastname: Yamamura
authors.forename: Jochen
authors.initials: J
authors.lastname: Herrmann
authors.forename: Reinhard E
authors.initials: RE
authors.lastname: Friedrich
authors.forename: Gerhard
authors.initials: G
authors.lastname: Adam
authors.forename: Victor F
authors.initials: VF
authors.lastname: Mautner
authors.forename: Thorsten
authors.initials: T
authors.lastname: Derlin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008099:Liver / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism; D009367:Neoplasm Staging; D018317:Nerve Sheath Neoplasms / Q000150:complications / Q000175:diagnosis* / Q000378:metabolism; D009456:Neurofibromatosis 1 / Q000150:complications / Q000175:diagnosis* / Q000378:metabolism; D010524:Peripheral Nervous System Neoplasms / Q000150:complications / Q000175:diagnosis* / Q000378:metabolism; D049268:Positron-Emission Tomography / Q000379:methods*; D012372:ROC Curve; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18